PETERSON: THE AMERICAN DICERATHERES. 



445 



practically equal, the height being sometimes very slightly greater than the breadth, 

 while in the recent rhinoceros the breadth is a little greater than the height. 

 The proximal facets of the scaphoid and cuneiform are not unlike those in recent 

 forms, while the lunar lacks the facet for the ulna, so plainly shown in the African 

 species. The large facets and the heavy palmar hook of the lunar uniting the 

 lateral bones on the proximal row of the carpals in R. hicornis are conspicuously 

 absent in Dicer atherium. The second row of the carpals in the latter are higher than 



Fig. 32. Fig. 33. 



Fig. 32. Diceratherium cooki Peterson. No. 2473, Coll. Carnegie Museum. Radial and dorsal views of 



ulna. X h 

 Fig. 33. Diceratherium cooki Peterson. No. 2499, Coll. Carnegie Museum. Oblique ulnar view of 



radius and ulna. X i. 



those in R. hicornis; otherwise there are only minor details of difference between 

 the two forms. With regard to size, the trapezium and metacarpal V have ap- 

 proximately the same proportions as in the living species. The three functional 

 metacarpals in D. cooki are decidedly longer, slenderer, and the shafts of II and IV 

 are more curved. This curvature of the shafts of Mc II and IV is to conform to 



